Buyer Beware: Rambling Post Caution: Many questions are posed - none are answered. I've been pondering some things I've seen posted here over the past few weeks along with a few (non-original I'm sure) thoughts of my own. Among them, in no particular order: Ron N - several links related to bamboo Del F - thoughts about floating soundboards in the bass region Del F - comments on Chickering's undercut or relief of some of their rims in the bass region Stephen B - comments on older makers who deliberately made rims lighter in an attempt to 'tune' the flexibility of the rim-soundboard system Del F - rims play no part in maintaining soundboard crown as soundboards are so compliant (is that the right word?) relative to rims Mason-Hamlin website - rim is absolutely essential in maintaining crown Various posters - discussions of waves, vibrations, etc. ad nauseum Conventional wisdom that rims should be massive to provide some sort of solid inert support for the soundboard My own observations that many pianos that I like the sound of have massive rims (both heavy and stiff) My own observations that many pianos with light or flexible rims have less than stellar sound To come somewhat to the point, I've been pondering whether rims should be massive or stiff or both and why? Should the mass and stiffness be uniform or should it vary and why? Some time ago I suggested that bamboo might be an interesting material for piano rims. Bamboo has very high strength and stiffness relative to its weight. If you take a maple rim as the standard then the bamboo rim could be stiffer and stronger while being lighter. Would this be a good thing? My experience is that the pianos I like have massive rims. However, if you look at wood property charts for American hardwoods you'll notice that density and stiffness go hand in hand. If you pick a denser wood you get a stiffer wood. So maybe the pertinent thing about the pianos I like is that they have stiffer rims, not more massive rims (the density is perhaps inconsequential). Also, the pianos with less massive or stiff rims that I don't tend to like tend to be low quality pianos. Perhaps the reason that the sound is less than stellar has to do with the design and quality of fit and finish rather than the fact that the rim is not massive or stiff. Perhaps the lightness or flexibility of the rim is coincidental. If the rim needs to be massive, then why? I've heard it said that it is 'to reflect waves' back into the soundboard. But I've also seen a few posts lately that suggest that waves don't travel in the soundboard. If the rim needs to be stiff, then why? Is it to resist the tendency of the perimeter of the board to move outward or inward as the board vibrates? If the board is so much more compliant than the rim then how does having a stiff rim help you? Is it to prevent the tendency of the perimeter of the board to move up and down as the board vibrates? If so it would make more sense to make the rim deeper rather than thicker, which seems to be contrary to accepted practice. If the rim needs to be stiff then why float the board or make undercuts in the rim at certain spots? Apparently the rim doesn't necessarily have to be stiff in these areas. Maybe the rim should be stiff or heavy in some areas but not in others. How do the rim braces fit into this? I've heard it said that they are only there to keep the belly rail from rolling. If the rim needs mass then the braces aren't helping much. You'd be better off putting the material into a thicker rim and eliminating the braces. If the rim needs stiffness then many brace configurations don't help much in certain directions. Many are good at increasing stiffness front to back but do almost nothing side to side. Do you only want the rim to be stiff in one direction and not the other? If you want soundboard flexibility is it a good idea to thin the rim as some of the old makers did? It seems you would transfer energy to the rim which isn't seemingly very efficient at transfering it to the air, but perhaps it is - there's a fair amount of surface area there. Perhaps you could carry this to an extreme and have the soundboard resting on a thin knife edge around the perimeter, as in a guitar or violin. Why would this be a bad idea? I'm interested in any thoughts or comments that you would care to share. Happy New Year. Phil F --- Phillip Ford Piano Service & Restoration 1777 Yosemite Ave - 215 San Francisco, CA 94124 -- Click here for your very own create-a-date adventure from MatchMaker Go to http://ecard.matchmaker.com/dating.html
This PTG archive page provided courtesy of Moy Piano Service, LLC